Current transmission system



Jan. 11, 1938. M. 1'. wxNTscH CURRENT TRANSMISSION SYSTEM F'iled July 3, 1936 2 Sheets-Sheet l CURRENT TRANSMISSION SYSTEM Filed July 5, 1936 2 sheets-sheet 2 gmc/WM- other type receiver is utilized to transmit rail Patented 1l, 1938 UNITED STATES .PATENT oFElcE' CURRENT TRANSMISSION SYSTEM Max Theodore Wintsch, Lancaster,\la. Application `July 3, 1936, Serial No. 88,907

` 1o claims.

`.This invention relates toa current transmitting system which may be utilized to operate automatic train control and cab-signaling systems. Therinvention more particularly comprehends a e continuously indicating or intermittently indicating automatic system in which an inductive or current to a vehicle operated on said track-rails, the .system herein described being immune against (l) Interference caused by foreign currents of diierent frequencies, or harmonics of the standard frequency of the controlling current transmitted inductively or directly by electrical roadside equipment.

(2) Vibration of the vehicle.

(3) Direct equalizing currents iiowing through the axle, back and forth, on railways propelled by direct current and a third rail system, where the wheels of the .vehicle do not make equally perfect electrical contact with the track rails.

(4) Adverse affectation by ordinary temperature changes.

One of the objects of the invention is the provision in a track-rail to vehicle current transmitting system of an inductive type receiver similar in construction to a closed core transformer. Another object of the invention is to provide such .a system and accompanying devices in which the rail current from one rail only is utilized to operate the system and devices. Another object of the invention is to provide in such systems a tuned-reed relay operating on the principle of a vibrating reed frequency meter. f

Other and equally important objects of the invention will be apparent hereinafter as the description ofthe invention proceeds.

Figure 1 of the drawings represents a diagrammatic showing of one preferred form of the system.

Figure' 2 is a view in side elevation of a tuned reed relay assembled in a casing.

Figure 3 is a view in front elevation of a relay comprising three groups of reeds.

Figure 4 is a top plan view of Figure 3.

Figure 5 is an end view of Figure 3.

Figure 6 is a detail of a single group of reeds.

Figure 'I is a top plan view of Figure 6, and

Figure 8 is a diagram of the pick-up circuit where more than one set cf vibrating reeds is used.

In the prior art, automatic train control systems are old where i ieir operation depends upon inductive fields that are produced from alternating currents flowing in the rails, the energy being induced or picked-up by means of open core transformers and collector coils, amplied and then transmitted to a relay carried on the locomotive. These prior art systems are subject to the disadvantage of picking-up harmonies of the frequencies at which they are de'- signed to operate; or of interference caused by foreign currents of different frequencies. vtheimore, their pick-up transformers are generally designed for receiving current from both rails ofthe track and involve more or less complicated structures. The present invention obviates the difficulties of the prior art and presentsa much more simple construction and design, with the added advantage of utilizing a single rail to transmit signaling current, so that the other rail may be used for the return path of propelling current. The use of a single rail to transmit signaling current by means of an inductiveopen core, single coil receiver is disclosed in the patent to Reichard 1,824,171 of September 22, 1931; and in my prior Patent 1,720,940 issued July 16, 1929, I have disclosed a tuned-reed single reed relay in a train control system, but neither of these patents disclose the novel combination and improved system that I am here claiming.

In Figure 1 of the drawings, the pick-up transformer is indicated by the numeral l and is of the closed core type having coils 2 mounted on opposite legs of the core and parallel with the vertical center line of one of the track rails 3, out of direct contact above the top of the rail. The two coils are serially wound in a direction opposing each other, so that an inductive iiux entering the coils from the track rail when a signal current is flowing through the rail, will act additively on the two coils. In actual operation, I have provided the closed core transformer with two coils on each leg of the core, the coils on each leg being connected in parallel; the coils on one leg connected in series with the coils on the other leg, so that induced currents in the coils are in opposition when ux threads each leg of the transformer in the same direction, and additive when fiux threads each leg in opposite direction. This receiver is suspended from the car underframe about 4 feet in advance of the first pair of wheels and about 7.5 inches above the level of the top of the rail, and is so mounted with respect to the railthat one coil of the receiver is located i-n a vertical plane approximately 4 inches outside of the righthand mail, while the other coil is similarly located approximately 4 inches inside the rlghthand rail. This inductive receiver (which has no direct wire connection with the rail) is connected to the primary of a balanced .winding in-put transformer I, the secondary of which is connected to the in-put circuit of a two-stage vacuum tube amplifier, the tubes being designated as 5 and 6. The out-put of amplifiers 5 and 6 are connected to the coils of a tuned-reedrelay 1 which is adjusted to vibrate on a band of frequencies corre- Fursponding to the frequencies of the track controlling current supplied to the rails. An assembly of such a relay is shown in Figure 2, with the details of the vibrating group or groups shown in Figures 3 to 7. In Figure 2, the letter A is the armature, D the amplitude adjusting screw, M the electro-magnet, and R the tuned reed. It will be noted from Figure 3 that the relay comprises three groups of reeds, each group consisting of three reeds secured to a support; one group being responsive to 25cycle current, a second group to 60 cycle current, and a third. group to 100 cycle current. This relay utilizes some construction features of the Frahm type or vibrating-reed frequency meter or Tachometer, in which instruments reeds are tuned to different natural periods of vibration to measure the frequency of cycle of electric current. The tuned-reed relay 'l differs in construction from the Frahm type instrument in that the relay has contacts on each of the reeds and stationary contact points mounted in the relay corresponding with contacts mounted on the reeds. The natural period of vibration of the tunedreed will not deviate from the standard more than one percent from the period upon which the reed is tuned to vibrate. On lower frequencies, deviation from the standard is as low as one-tenth of one percent. I therefore prefer to me several reeds to cover a whole band of frequencies of the controlling fcurrent. For example, if the frequency of the controlling current is 25 cycles, one reed is tuned to vibrate on exactly 25 cycles, and several other reeds are tuned to vibrate on one-quarter cycle either way from the standard, each reed one-quarter cycle higher or lower than the preceding reed either direction from the reed tuned to the standard of 25 cycles. In other words, the reeds may be tuned to a Whole band of frequencies, as 23.5, 23.75, 24, 24.25, 24.5, 24.75, 25, 25.25, 25.5, etc. as conditions may require. The construction is such that the reeds may contact at about 1% of the iull amplitude of their natural amount of vibration. These reeds, being provided with contacts which make and break in rapid succession at the frequency to which the reeds are tuned, control the flow of current from a small battery 8 to the grid oi.' vacuum tube S located betweenv the tuned-reed relay 'l and the master relay Ill, the coils of which are included in the plate circuit of the tube 9.

A compensation condenser I l is charged by the battery 8 each time the contact "a" in the tunedreed relay is closed, and the condenser II releases its charge slowly through the grid and 'cathode of the amplifier tube l each time the contact a is broken.' As long as the grid is carrying a positive charge, the plate circuit for the tube 9 will be closed. The coil of the masterreiay Ill is connected to the secondary winding I2 of a transformer i3 having aprimary winding i4 which in turn is connected to the plate I 5 of the amplifier tube 9 and to the B+ supply. The master-relay in turn actuates the cab-signal apparatus in accordance with track conditions.

A detailed description or the operation oi.' the radio amplifying tubes, and particularly tube 9 shown in Figure 1 of the drawings, is as follows:

Inside of the glass envelope of the radio tube 8 in a vacuum we have four electrodes which are the heating lament, the cathode which supplies the electrons for the operation of the tube while it is heated by the filament, the grid which controls the flow of electrons from the plate to the cathode, and the plate. In practice, the lament is in the center, around the filament is the cathode, around the cathode we have the grid which is composed of a wire mesh, and on the outside of the grid is located the plate. As long as the cathode is made incandescent by the heated iliament, negative electrons are thrown off into the space around the cathode. The negative electrons are attracted by the plate which is always connected to the positive pole oi the B current supply, the electronic current ilowing through the mesh oi' the grid tothe plate. It is a known fact that electric current will ilow only from a zone 'of high, or positive potential to one of low or negative potential. Hence, the B" supply current will ilow inside of the tube from the plate grid-cathode circuit because a certain number of electrons are stopped by the positively charged grid and allows the current of the B supply to flow in the circuit in which case we have a gridcathode current. The flow of electrons from the cathode, when the grid is negativ, is repulsed, for in this case the electrons are negatively charged, since we know that two polarities of the same name repulse one another. Therefore, the current from the plate, having no electronic support to travel on, is then quitesuddenly stopped. One can understand from this explanation that the grid acts as an automatic interrupter, but since no mechanical parts are to be moved it has no inertia, and it can therefore open and close the circuit of the plate a tremendous nurnber of times per second.

Since we now know that changing the polarity of the grid in our tube 9 from positive to negative opens and closes the plate circuit by means of an alternating current supplied from the current supply I, which may be a 48 volt battery, and regularly interrupted by the vibrating reed at the contact a at a speed corresponding to the frequency of the track control current.

Assuming a 100 cycle control current is flowing in the track rail I, this current is then inductively transmitted by means of the pick-up transformer to the input of a two stage audio frequency amplifier of the electronic type, located on the propelling vehicle. The operating coils of the vibrating-reed relay will become energized or de-energized corresponding to the frequency of the alternations of the track control current. The reed l which has a natural period of vibration also corresponding to the frequency of the alternations of the track current will now open or close the contact a 100 times per second. Every time the reed 1 closes the contact a, a grid-cathode current will ilow from the positive pole of the current supply I, through the reed 7, through the contact a to the grid and through the cathode in the tube 9 to the negative pole of the current supply 8. This same current will also place a static charge on the compensating condenser Ii. The path for the plate-cathode "B current including serially connected therewith the operating coil I0 of our master relay.

is now'closed, by action of the positively charged grid. -The coil l ofthe masterl relay will become energized and will pick up its armatures.

Now when the contact a in the vibrating reed relay is open, the grid in the tube 9 becomes negatively charged being connected to the negative v pole of the B current supply. The flow of electrons from the cathode when the ygrid is negative is repulsed since the electrons are now negatively charged, therefore the plate-cathode current having no electronic supportto travel on', is now interrupted. The supply of B current to the coil I0 of the master relay becomes therefore interrupted and the relay will release its armatures. However, asl explained previously, as long as the contact a inthe vibrating-reed relay was closed, the compensating .condenser Il was statically charged. With the contact a open the condenser Il will release its static Icharge through the grid-cathode circuit, momentarily acting in the same manner as the current supply 8. The plate-cathodecircuit inside of the tube 9 will therefore remain closed and the B current supply` will keep the coil I0 of the master relay energized.

If thecurrent supply to the input ofthe two stage audio amplifier in advance of the coils of the vibrating reed relay becomes permanently interrupted, the tuned reed 1 will no longer vibrate. 'I'he contact a will remain open, the plate-cathode circuit in the tube 9 will be permanently interrupted and the master relay will remain in the open position.

Any suitable circuit may be employed for operating the cab-signals by reason of the energizing and deenergizing of the master relay, but I prefer to use the wayside signal and vehicle circuits and mechanism described and claimed in my two copending United States applications, Ser. No. 37,878, filed August 26, 1935 and Ser. No. 748,252, led October 15, 1934.

Any desired signaling or controlling mechanism may be eiectuated through the single master relay, or a plurality of relays similar to the master relay Ill may be provided, each controlled by a reed-relay which is responsive to a predetermined frequency.

The tuned-reed relay may operate on an input current of approximately'l-Z milliamperes at a voltage of 15 volts or more and a controlling track current of 1.5 to 2 amperes at 1/2 volt. The number of stages of vacuum tube amplication required in advance ofthe reed-relay will be determined by the frequency of the controlling current. Three stages of amplification are used if the frequency is near 25 cycles, while only one stage of amplification will suiiice ifthe frequency is above 60 cycles. In order to operate the master relay one stage of amplification is shown. Additional stages may be used, if desirable or necessary.

It may be observed that no electrical iilter is required in the pick-up circuit and the tunedreed relay makes the device more selective to particular frequencies. The invention has been described with one set of reeds on the basis of a 25 cycle current, but as many sets of reeds may be used as desired. They may be manually adjustable and interchangeable. As described hereinabove, and with particular reference to Figure 3, a number of sets may be provided together ticular signaling system' of the territory overv which the train might pass. This will be oi especial advantage where a train operating in a territory where the signals are on a 100 cycle frequency passes into a territory where the frequency is, say 60 cycles.

In an actual installation of the present system, tests were made to determine the eifect of foreign current from adjacent power lines of the same frequency as that used for the operation of the device. To simulate the effect of an adjacent power line, a wire loop incorporating a slide wire resistance and an ammeter was connected to a 25 cycle power supply, this being the frequency at which the installation was designed to operate. This loop, carrying 5 amperes was gradually moved ytoward the receiver, and when it had been brought to within 12 inches of the receiver, the red-cab signal indication was extinguished and the green cab-signal was displayed. With amperes in the loop, it was necessary to bring the wire within 18 inches of the receiver in order to extinguish the red and display the green indication. 'I'hese tests were made with no rail current present in the rails, simulating the conditions whichshould obtain in an occupied block. These tests indicate the comparative immunity of the device from the inductive effects of adjacent power lines and other electric roadside equipment such as. generators, transformers, etc.

Various modifications may be made within the spirit and scope of the invention, and I do not Wish to be slavishly restricted to the details as set forthherein, but desire to claim the invention as broadly as set forth in the appended claims. 'I'he pick-up system might be used on steam propelled locomotivesand the tuned-reed relay control for the signals and/or train control could be used, without regard to the specific type of pick-up utilized.

What I claim is:

'1. In a current transmitting system in which the rails of a track section are supplied with alternating current of a predetermined stand.

ard cycle for control of train carried apparatus, a train-carried receiving circuit including a relay in said circuit having a set of reeds each carrying contacts and tuned to a band of frequencies approximating and including said predetermined standard cycle, said tuned-reed relay being selectively independent of ltering means, and another circuit including a masterrelay controlled by current flowing through the reeds and contacts in said tuned-reed re1ay,said reeds and contacts being included in the circuit of the master-relay.

2. A current transmitting system in which the rails in one section of a track are supplied with alternating current of a predetermined cycle and in another section are supplied with alternating current of another predetermined cycle, said current being supplied for control of train carried apparatus, and a vehicle provided with a receiving apparatus responding selectively to the frequencies of the rail current, said receiving apparatus having a circuit including a tuned-reed relay selectively independent of filtering means and having a plurality of sets of reeds capable of vibrating at bands approximating and including said respective predetermined whereby said receiving apparatus is effective for operation in both sections.

3. A current transmitting system in which the rails of a track section are supplied with alter- ,ceiver for said control current, a tuned-reed refrequencies, y

nating current for control of train carried apparatus, and a vehicle provided with a receiving apparatus having a circuit including a tuned-reed relay selectively independent of ltering means and having a plurality of sets of reeds, each set responding to a desired standard frequency band approximating a predetermined standard cycle.

4. The system set forth in claim l in which a closed core type transformer inductively receives the rail current, said transformer comprising a laminated core with coils mounted on two opposite legs thereof, the coil on one leg being connected serially with the coil on the other leg whereby induced currents in the coils are in opposition when flux threads each leg of the transformer carrying the coils in the same direction, and additive when flux threads each leg of the transformer carrying the coilsin opposite direction; such transformer eliminating stray interfering currents.

5. In a current transmitting system in which the rails of a track section are supplied with a source of current of a predetermined standard cycle at times subject to fluctuations from said standard cycle, a train-carried receiving circuit including a receiver capable of inductively receiving said current, a balanced winding in-put transformer in said circuit having its primary winding connected to said receiver, multi-stage electronic tube amplifiers in said circuit, means connecting the secondary winding of 'said transformer to the in-put of said amplifier, a tunedreed relay in said receiving circuit selectively independent of filtering means and provided with a plurality of reeds having contacts capable of making and breaking in rapid succession at the frequency to which each of the reeds is tuned, said reeds being tuned to a frequency band approximating and including said standard cycle whereby fiuctuations from said standard cycle will be compensated for, means connecting the out-put of the said amplifier to said tuned-reed relay, another circuit including a master-relay,

an electronic tube amplifier having its grid and plate circuits respectively connecting the circuits of the tuned-reed relay and the master-relay, and means actuated by the master-relay.

6. In a current transmitting system in which the rails of a track section are supplied with a source of current of a predetermined standard frequency at times subject to fluctuations from said standard frequency, a train-carried receiving circuit including a receiver, a balanced winding in-put transformer having its primary winding connected to said receiver, a multi-stage electronic tube amplifier in said circuit, means connecting the secondary of said transformer to the in-put of said amplifier, a tuned-reed relay in said receiving circuit selectively independent of filtering means and provided with a plurality of reeds having contacts capable of making and breaking in rapid succession at the frequency to which each of the reeds is tuned, at least one of said reeds being tuned to a frequency slightly lower than the predetermined frequency and another slightly higher than the predetermined frequency, means connecting the out-put of said amplifier to said tuned-reed relay, another circuit including a master-relay, an electronic tube amplifier having its grid and plate circuit respectively connecting the circuits of the tuned-reed relay and the master-relay, and means actuated by the master-relay.

7. In a current transmitting system in which the rails of a track section are supplied with a source of current of a predetermined standard frequency at times subject to fluctuations from said standard frequency, a train-carried circuit including means for receiving said current, means in said circuit for amplifying the received current, tuned-reed relay means in said circuit selectively independent of filtering means and having a plurality of reeds tuned to a band of frequencies including and approximating said predetermined standard cycle, said relay having its coils connected with said amplifying means and having its reeds in make and break circuit connection with other amplifying means, and another circuit including master-relay means connected to said other amplifying means.

8. A current transmitting system in which the rails in one track section are supplied with alternating current of a predetermined cycle and another track sectlon are supplied with alternating current of another predetermined cycle, said current being supplied for control of train carried apparatus, a vehicle provided with a vehiclecarried circuit including a receiving apparatus capable of picking up current from a rail in each of said sections, means in said circuit for amplifying said current, tuned-reed relay means in said circuit selectively independent of filtering means and having a plurality of sets of reeds, each of said sets respectively being tuned to bands of frequencies approximating and including predetermined standard cycles, whereby each set may vibrate on a different frequency of different control currents ln different track sections, and another circult including a master-relay controlled by said sets of reeds.

9. In a current transmitting train-control system, a source of current of a predetermined standard frequency at times subject to fluctuations from said standard frequency, a rail supplied with a vehicle-carried circuit including said current, a vehicle provided with a receiving apparatus responding selectively to the frequency of the rail current, said circuit including a tunedreed relay selectively independent of filtering means and having a plurality of reeds tuned to a band of frequencies approximating and including said predetermined standard frequency, said reeds being tuned to vibrate one-quarter cycle apart from each other successively, and another circuit including a master-relay controlled by said reed relay.

10. In a current transmitting train-control system, a vehicle provided with a. vehicle-carried circuit including a receiving apparatus capable comprising an electronic tube having a grid lnl1 series connection with a condenser and resistor, said condenser and resistor being ln series make and break circuit connection with said vibrating reeds, and a battery in make and break circuit connection with said condenser and resistor and said grid and operable to apply current to the grid by building up a static charge in the condenser during a period of impulse of the reeds when the same are in contacting circuit with the grid and the condenser releasing its static charge through the grid-cathode circuit of the electronic tube when the reeds are out of contacting circuit with the grid.

MAX THEODORE WINTSCH. 

